Imports fell 3.2% to 3,160bn yen, helping the current account surplus hit 1,090bn yen, 21.7% up on the April 2001 figure.

Observers said the figures reflected the shock burst of growth Japan registered in the first three months of the year.

Ministry of Finance figures indicated that the economy expanded by 1.4% over the quarter, a rate which - if continued for a full year - would amount to 5.7% growth.

But with growth focused around in exports, and doubts over whether it is feeding through to small business, services and households, holding onto that pace of expansion is widely seen as unlikely.

Steeling itself

One risk to exports comes with the US tariffs on steel introduced earlier this year.

Japan has been mulling how to strike back.

But while the European Union has now approved a list of retaliatory sanctions, Japan has decided to put them off indefinitely, in the hope that the US will be persuaded to grant exemptions.

An hour-long conversation between US trade representative Robert Zoellick and Takeo Hiranuma, Japan's economy, trade and industry minister, produced assurances that the US was prepared to be "constructive" about exemptions.